Method for preparing silicone hydrogels

1. A silicone hydrogel ophthalmic device, comprising a silicone hydrogel material which is obtained by copolymerizing, at a temperature of about 80° C. or above, a solvent-free polymerizable fluid composition comprising (a) from about 20 to about 46% by weight of a siloxane-containing macromer with ethylenically unsaturated group(s), (b) from about 10% to about 30% by weight of a siloxane-containing vinylic monomer; (c) from about 15% to about 50% by weight of a hydrophilic vinylic monomer, (d) from about 0.2% to about 1% by weight of a radical initiator, (e) from about 5% to about 20% by weight of a blending vinylic monomer; and (f) an amount of an organonitrioxide sufficient to have a ratio of percentage by weight of the organonitroxide to the radical initiator in the polymerizable fluid composition being from about 0.3 to about 1.1 and being selected to enable the polymerization fluid composition to be cured at an elevated temperature to obtain the silicone hydrogel material having a good quality, an oxygen permeability of at least about 40 barres and a modulus of about 1.5 MPa or less and a water content of at least about 15% by weight when fully hydrated, wherein the organonitrioxide is a compound having the formula of

in which R 1 , and R 2 are independently H, an alkyl group, a cycloalkyl group, an arenyl group, a heterocyclic group, or an aryl group; R 3 is an alkyl group, a cycloalkyl group, an arenyl group, a heterocyclic group, or an aryl group; R 3 and R 2 or R 1 and R 2 may be joined together to form a cyclic ring structure that may have fused with it another saturated or aromatic ring; each of R 1 , R 2 , or R 3 may be substituted by at least one member of the group consisting of hydroxyl group, sulfonate group, sulfate group, carboxylate group, amino group, ammonium group, alkoxy group, aryloxy group, silyl group, boryl group, phosphino group, thio group, seleno group, and combinations thereof, wherein the silicone hydrogel material has a predominant glass-transition temperature of about 25° C. or higher.

2. The silicone hydrogel ophthalmic device of claim 1 , which is a contact lens.

3. The silicone hydrogel ophthalmic device of claim 1 , wherein the ophthalmic device has an oxygen permeability of at least about 50 barrers.

4. The silicone hydrogel ophthalmic device of claim 3 , wherein the ophthalmic device has a elastic modulus of about 1.2 MPa or less.

5. The silicone hydrogel ophthalmic device of claim 4 , wherein the polymerizable fluid composition further comprises one or more members selected from the group consisting of a hydrophilic vinylic monomer, an antimicrobial agent, a silicon-containing vinylic monomer, a blending vinylic monomer, a cross-linking agent, an UV-absorbers, and a visibility tinting agent.

6. The silicone hydrogel ophthalmic device of claim 4 , wherein the blending vinylic monomer is an aromatic vinylic monomer, a cycloalkyl-containing vinylic monomer, a Tg-enhancing vinylic monomer, or a mixture thereof, wherein the Tg-enhancing vinylic monomer is selected from the group consisting of acrylic acid, C 1 -C 10 alkyl methacrylate, methacrylonitrile, acrylonitrile, C 1 -C 10 alkyl acrylate, N-isopropyl acrylamide, 2-vinylpyridine, and 4-vinylpyridine.

7. The silicone hydrogel ophthalmic device of claim 6 , wherein the blending vinylic monomer is an aromatic vinylic monomer which is styrene, 2,4,6-trimethylstyrene (TMS), t-butyl styrene (TBS), 2,3,4,5,6-pentafluorostyrene, benzylmethacrylate, divinylbenzene, or 2-vinylnaphthalene.

8. The silicone hydrogel ophthalmic device of claim 6 , wherein the blending vinylic monomer is a vinylic monomer containing a cyclopentyl, cyclohexyl or cycloheptyl, which can be substituted by up to 3 C 1 -C 6 alkyl groups.

9. The silicone hydrogel ophthalmic device of claim 4 , wherein the hydrophilic vinylic monomer is N,N-dimethylacrylamide (DMA), 2-hydroxyethylmethacrylate (HEMA), 2-hydroxyethyl acrylate (HEA), hydroxypropyl acrylate, hydroxypropyl methacrylate (HPMA), trimethylammonium 2-hydroxy propylmethacrylate hydrochloride, dimethylaminoethyl methacrylate (DMAEMA), glycerol methacrylate (GMA), N-vinyl-2-pyrrolidone (NVP), dimethylaminoethylmethacrylamide, acrylamide, methacrylamide, allyl alcohol, vinylpyridine, N-(1,1dimethyl-3-oxobutyl)acrylamide, acrylic acid, methacrylic acid, or a mixture thereof.

10. The silicone ophthalmic device of claim 1 , wherein the blending vinylic monomer is an aromatic vinylic monomer, a cycloalkylmethacrylate, a cycloalkylacrylate, or a mixture thereof.

11. The silicone hydrogel ophthalmic device of claim 4 , wherein the polymerizable fluid composition further comprises silver nanoparticles in an amount sufficient to impart to the resultant silicone hydrogel material an antimicrobial activity characterized by having at least a 5-fold reduction (≧80% inhibition) of viable microorganisms (e.g., Pseudomonas aeruginosa GSU #3, or Staphylococcus aureus ATCC #6538).

12. A silicone hydrogel material, which is obtained by copolymerizing, at a temperature of about 80° C. or above, a polymerizable fluid composition comprising (a) from about 20 to about 46% by weight of a siloxane-containing macromer with ethylenically unsaturated group(s), (b) from about 10% to about 30% by weight of a siloxane-containing vinylic monomer; (c) from about 15% to about 50% by weight of a hydrophilic vinylic monomer, (d) from about 0.2% to about 1% by weight of a radical initiator, (e) from about 5% to about 20% by weight of a blending vinylic monomer; and (f) an amount of an organonitrioxide sufficient to have a ratio of percentage by weight of the organonitroxide to the radical initiator in the polymerizable fluid composition being from about 0.3 to about 1.1 and being selected to enable the polymerization fluid composition to be cured at an elevated temperature to obtain the silicone hydrogel material having a good quality, an oxygen permeability of at least about 40 barres and a modulus of about 1.5 MPa or less and a water content of at least about 15% by weight when fully hydrated, wherein the organonitrioxide is a compound having the formula of

in which R 1 , and R 2 are independently H, an alkyl group, a cycloalkyl group, an arenyl group, a heterocyclic group, or an aryl group; R 3 is an alkyl group, a cycloalkyl group, an arenyl group, a heterocyclic group, or an aryl group; R 3 and R 2 or R 1 and R 2 may be joined together to form a cyclic ring structure that may have fused with it another saturated or aromatic ring; each of R 1 , R 2 , or R 3 may be substituted by at least one member of the group consisting of hydroxyl group, sulfonate group, sulfate group, carboxylate group, amino group, ammonium group, alkoxy group, aryloxy group, silyl group, boryl group, phosphino group, thio group, seleno group, and combinations thereof, wherein the silicone hydrogel material has a predominant glass-transition temperature of about 25° C. or higher.